This application claims priority to an application entitled xe2x80x9cDevice for Controlling Connection of Built-in Type Ear-Microphone for Portable Radio Terminalxe2x80x9d filed in the Korean Industrial Property Office on Nov, 7, 1998 and assigned Serial No. 98-47903, and an application entitled xe2x80x9cCircuit for Controlling the Connection of a Built-in Type Earphone-Microphone for Portable Radio Terminalxe2x80x9d, filed in the Korean Industrial Property Office on Nov. 7, 1998 and assigned Serial No. 98-47904, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates generally to a portable radio terminal, and in particular, to a device for controlling the connection between a built-in type ear-microphone and a portable radio terminal.
2. Description of the Related Art
An ear-microphone used with a portable radio terminal can be classified into either an internal (or built-in) type or an external type. The built-in type ear-microphone commonly includes a three-pole type plug which is inserted into a jack typically on the top or side of the portable radio terminal. An external type ear-microphone includes a plug which is inserted into an interface connector mounted at the bottom of the portable radio terminal.
FIG. 1A is a perspective view illustrating the connection between a built-in type ear-microphone and a portable radio terminal, and FIG. 1B is a perspective view illustrating the connection between an external type ear-microphone and a portable radio terminal. FIG. 2 illustrates a conventional device for controlling connection of the built-in type ear-microphone.
Referring to FIGS. 1A and 2, when the plug 200 of a built-in ear-microphone is mechanically connected to an ear-microphone jack 100, the user can make a telephone conversation through the ear-microphone. As stated above, the ear-microphone jack 100 is typically located at the top or side of the terminal. More specifically, as shown in FIG. 2, the ear-microphone jack 100 has pins 1, 3 and 2, which are connected to ground node G, speaker node S and microphone node M, respectively. Therefore, a microphone 250 and a speaker 260 of the ear-microphone are electrically connected to a microphone amplifier AMP1 and a speaker amplifier AMP2 prepared in a vocoder 130, respectively, allowing the user to make a telephone conversation. A comparator COM1 compares an electric signal sensed at a pin 4 in the ear-microphone jack 100 with a reference voltage Vref to generate a jack detection signal JD1 representative of whether or not the plug 200 is inserted into the jack 100. In addition, the jack detection signal JD1 is an initial detection signal for generating a signal having a level appropriate for the ear-microphone.
FIG. 3 illustrates a conventional external type ear-microphone. An interface connector 140 mounted at the bottom of the terminal includes ports 140a and 140b for connection of the ear-microphone. Though not shown, the interface connector 140 further includes ports for a hands-free kit and ports for data communication. More specifically, when a plug 230 shown in FIG. 1B is inserted into the interface connector 140, the microphone 250 and the speaker 260 are electrically connected to the microphone amplifier AMP1 and the speaker amplifier AMP2 prepared in the vocoder 130, respectively, thus allowing the user to make a telephone conversation.
When the built-in type ear-microphone, which is commonly used in code division multiple access (CDMA) portable radio terminals, is inserted during the telephone conversation, unpleasant noises are generated. This is because the microphone is instantaneously short-circuited to the speaker when the ear-microphone is inserted.
Meanwhile, GSM portable radio terminals employing a time division multiple access (TDMA) technique have the following problems in addition to the problems mentioned above.
In general, the external type ear-microphone is typically used with TDMA portable radio terminals, while the built-in type ear-microphone is typically used with CDMA portable radio terminals. This is because, while the CDMA terminal has a low instantaneous power consumption of 0.6 W, the TDMA terminal has a high instantaneous power consumption of 2 W, thereby causing a degradation of audio quality due to TDMA noises. Another reason that the external type ear-microphone is used with TDMA terminals is that TDMA terminals lack internal space. However, the external type ear-microphone used with GSM portable radio terminals is unhandy to carry about and restricts movement of the user, because the ratio of the size of the plug to the size of the portable radio terminal is very high.
In addition, when using the ear-microphone, the GSM terminal cannot use the interface connector for other uses. For reference, to solve the problem of the external ear-microphone, Nokia company has proposed a TDMA portable radio terminal which uses the built-in type ear-microphone by employing a single ended technique which is used in CDMA portable radio terminals. In the single ended technique, a voice signal and the other mode is used as a ground. By contrast, in the double ended technique, both nodes are used to transmit the voice signal, however, there is a phase difference between the nodes. Although the single ended built-in type ear-microphone is effective in detecting switching of the ear-microphone, it is susceptible to TDMA noises, causing deterioration of audio quality. Unfavorably, employment of the single ended technique causes a decrease in volume of the audio. The double ended technique is less susceptible to TDMA noises than the single ended technique because the noise is more readily canceled, however, it requires two speakers and two microphones.
FIG. 4 illustrates a device for controlling connection of a single ended ear-microphone. Referring to FIG. 4, the conventional device includes a 3-pole 5-node earphone jack 430 into which an earphone plug is inserted; a vocoder 400 for processing audio signals input and output to/from an earphone, and a speaker and a microphone of the terminal; a reference voltage generator 410 for generating a reference voltage; and a voltage comparator 420 for comparing a variation in voltage, which happens when the earphone plug is inserted in the earphone jack 430, with the reference voltage generated. from the reference voltage generator 410, to notify the controller of the insertion of the earphone plug. Therefore, in the TDMA portable radio terminal, it is very difficult to implement a built-in type ear-microphone which is insusceptible to the TDMA noises.
Therefore, there is a need for a device that controls the connection of a built-in type ear-microphone, which can prevent the unpleasant noises generated in the CDMA terminal, and have reduced susceptibility to the TDMA noises generated in the GSM terminal.
It is, therefore, an object of the present invention to provide a device for controlling the connection of an ear-microphone, which is handy to carry about, with a portable radio terminal, and for preventing generation of unpleasant noises even when the ear-microphone is inserted during telephone conversation.
It is another object of the present invention to provide a device for connecting an ear-microphone, which can be built in a TDMA portable radio terminal and minimize susceptibility to TDMA noises.
It is further another object of the present invention to provide an earphone device which can detect switching and insertion of an earphone.
It is still another object of the present invention to provide a device for controlling the connection of a double ended ear-microphone with a TDMA portable radio terminal.
In accordance with one embodiment of the present invention, a device for controlling the connection of a built-in type ear-microphone with a portable radio terminal, comprises a vocoder including the speaker and microphone amplifiers of the portable radio terminal and the ear-microphone amplifier; a first logic combination means for logically combining a signal output from the speaker amplifier and a signal output from the ear-microphone so as to prevent generation of noises due to the short-circuit of the microphone signal and the speaker signal when the ear-microphone plug is inserted in the ear-microphone jack; a comparator for comparing an electric signal sensed at the ear-microphone jack with a reference voltage; a second logic combination means for logically combining the output-of the first logic combination means and the output of the comparator to generate a jack detection signal; and a central processing unit for generating a control signal for enabling the vocoder to switch an audio signal path to the ear-microphone amplifier, upon detection of the jack detection signal during a call.
In another embodiment of the present invention, a device for controlling the connection of a built-in type ear-microphone with a time division multiple access (TDMA) portable radio terminal, comprises a vocoder, including positive and negative nodes for a speaker and a microphone, for processing audio signals input and output from and to the nodes; a doubled ended 4-pole 6-node earphone jack for connecting, upon insertion of an earphone plug, a positive line of an ear-microphone to a microphone positive node of the vocoder through a first node, connecting a negative line of the ear-microphone to a microphone negative node of the vocoder through a second node, and disconnecting the second node from a third node; and a voltage comparator for comparing a voltage input through the first or third node with a reference voltage, in order to detect the switching of an earphone switch and insertion of the earphone plug.